New Near‐Infrared‐Fluorescent Aza‐BODIPY Dyes with 1‐Methyl‐1 H‐Pyrrolyl Substituents at the 3,5‐Positions

New near-infrared-fluorescent aza-BODIPY dyes with 1-methyl-1H-pyrrolyl substituents at the 3,5-positions were successfully prepared and the 1-methyl-1H-pyrrolyl groups had a noticeable effect on their photophysical properties. The absorption and emission maxima of aza-BODIPY dye 4 ((abs)=754nm, (em)=803nm) that contained 1-methyl-1H-pyrrolyl groups were bathochromically shifted compared to those of typical aza-BODIPY dye 1 ((abs)=649nm, (em)=673nm), which contained phenyl groups. The photophysical data were well-supported and explained by MO calculations. Aza-BODIPY dye 3 was stable and suited for labeling living cells for imaging assays in the near-infrared region.